import { Injectable, ExecutionContext, Inject } from '@nestjs/common';
import { Reflector } from '@nestjs/core';
import { ThrottlerGuard, ThrottlerStorage, getOptionsToken, getStorageToken } from '@nestjs/throttler';
import { SystemConfigService, CONFIG_KEYS } from '../modules/system-config/system-config.service';

// Route-prefix → throttler tier mapping.
// Evaluated in order; first match wins.
const ROUTE_TIERS: Array<{ prefix: string; tier: 'auth' | 'strict' | 'default' }> = [
  { prefix: '/auth',              tier: 'auth'   },
  { prefix: '/fayda/verification',tier: 'auth'   },
  { prefix: '/bookings',          tier: 'strict' },
  { prefix: '/passengers',        tier: 'strict' },
  { prefix: '/payments',          tier: 'strict' },
  { prefix: '/wallet',            tier: 'strict' },
];

@Injectable()
export class DynamicThrottlerGuard extends ThrottlerGuard {
  constructor(
    @Inject(getOptionsToken()) options: any,
    @Inject(getStorageToken()) storageService: ThrottlerStorage,
    reflector: Reflector,
    private readonly systemConfig: SystemConfigService,
  ) {
    super(options, storageService, reflector);
  }

  async canActivate(context: ExecutionContext): Promise<boolean> {
    if (context.getType() !== 'http') {
      return true;
    }

    const [authLimit, authTtl, strictLimit, strictTtl, defaultLimit, defaultTtl] =
      await Promise.all([
        this.systemConfig.getNumber(CONFIG_KEYS.THROTTLE_AUTH_LIMIT),
        this.systemConfig.getNumber(CONFIG_KEYS.THROTTLE_AUTH_TTL_MS),
        this.systemConfig.getNumber(CONFIG_KEYS.THROTTLE_STRICT_LIMIT),
        this.systemConfig.getNumber(CONFIG_KEYS.THROTTLE_STRICT_TTL_MS),
        this.systemConfig.getNumber(CONFIG_KEYS.THROTTLE_DEFAULT_LIMIT),
        this.systemConfig.getNumber(CONFIG_KEYS.THROTTLE_DEFAULT_TTL_MS),
      ]);

    const url: string = context.switchToHttp().getRequest<{ url: string }>().url ?? '';
    const matched = ROUTE_TIERS.find(({ prefix }) => url.startsWith(prefix));
    const tier = matched?.tier ?? 'default';

    if (tier === 'auth') {
      this.throttlers = [{ name: 'auth', ttl: authTtl, limit: authLimit }];
    } else if (tier === 'strict') {
      this.throttlers = [{ name: 'strict', ttl: strictTtl, limit: strictLimit }];
    } else {
      this.throttlers = [{ name: 'default', ttl: defaultTtl, limit: defaultLimit }];
    }

    return super.canActivate(context);
  }
}